An electronic system can include multiple devices, such as integrated circuits. An electronic device can include circuitry to interface with another device. For example, an integrated circuit can include an output terminal and an associated output driver for transmitting information to another integrated circuit. The information can be encoded and transmitted using a voltage or a current signal. For example, an output driver can include push-pull circuitry to provide a signal where the information to be transmitted is encoded using discrete voltage levels corresponding to a logic-high or a logic-low state. Alternatively, an output driver can selectively enabled to sink current provided by external pull-up circuitry, where particular levels of the sink current corresponding to individual logic states. Furthermore, an output driver can provide an analog interface, in which case the output driver provides a continuously range of voltage or current instead of discrete levels. Many failures that can occur within an electronic device can be detected using testing protocols and associated test circuitry. For example, the logic state of latch devices can be evaluated using test-scan technology. Other forms of built-in self-test can validate the operation of a functional block by providing diagnostic stimulus and evaluating how the functional block responds to the stimulus. Faults associated with output drive circuits can be difficult to identify, especially while the electronic system is functioning in its normal operating mode. Faults associated with an output driver can include defective transistors in the driver circuit, broken or shorted bonding wires, damaged cables or connectors that couple the output signal to the receiving device, failed electrostatic-discharge protection components, defective printed circuit board conductors, and the like. Undetected faults can have serious implications. For example, a fault in an automotive emergency braking system can result in a collision.
The use of the same reference symbols in different drawings indicates similar or identical items.